The present invention relates generally to the field of semiconductor devices, and more specifically, to fabrication of a structure and method of forming self-aligned punchthrough stop (PTS) doping in bulk finFET by reflowing doped oxide.
In using field effect transistors in the formation of ultra large scale integrated circuit devices, punchthrough has increasingly become an issue. Punchthrough ion implantations have been used near the source and drain to reduce the electric field in the channel thereby increasing the punchthrough voltage. These methods have had the problem of increasing the source and drain capacitance thereby adversely effecting device performance.
The term finFET refers to a field effect transistor (FET) with fins. In one case, the finFET is used to describe a nonplanar, double-gate transistor that may be built on a silicon-on-insulator (SOI) substrate. The distinguishing characteristic of the finFET is that the conducting channel is wrapped by a thin silicon “fin”, which forms the body of the device. The thickness of the fin (measured in the direction from source to drain) determines the effective channel length of the device. The wrap-around gate structure provides a better electrical control over the channel and thus helps in reducing the leakage current and overcoming other short-channel effects.